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Resultados 1101-1110 de 3,208
Monosaccharide anhydrides, monocarboxylic acids and OC/EC in PM1 aerosols in urban areas in the Czech Republic Texto completo
2015
Křůmal, Kamil | Mikuška, Pavel | Večeřa, Zbyněk
The concentrations of monosaccharide anhydrides (levoglucosan, mannosan, galactosan), monocarboxylic acids (alkanoic acids C7 – C20 and two unsaturated fatty acids, palmitoleic and oleic acids) and organic and elemental carbon in PM1 aerosol samples were measured in two cities of the Czech Republic (Brno and Šlapanice) in winter and summer seasons of 2009 and 2010.Mass concentrations of PM1 aerosols (determined by weighing filters with collected aerosol) were higher in winter than in summer in both 2009 and 2010, in Brno as well as in Šlapanice.Organic compounds were analysed by GC–MS. The sum of average atmospheric concentration of monosaccharide anhydrides (MAs) in PM1 aerosol in Brno and Šlapanice was 273 and 646 ng m−3 in winter and 20–42 ng m−3 in summer. The higher concentrations of MAs in PM1 aerosols in winter seasons indicate higher frequency of biomass combustion than in summer seasons. Levoglucosan was the most abundant monosaccharide anhydride. Contrary to MAs, the concentrations of majority monocarboxylic acids were higher in summer (153–221 ng m−3) than in winter (116–206 ng m−3) in both cities in 2009 and in 2010. Palmitic acid was the most abundant monocarboxylic acid.The concentrations of both organic (OC) and elemental (EC) carbon were higher in winter than in summer, which corresponds especially to higher biomass burning and coal combustion in the frame of residential heating within winter seasons. Mass concentrations of the analysed aerosol samples were counted, i.e., OCBB and ECBB (biomass burning), OCFF and ECFF (fossil fuel combustion), and OCBIO (biogenic sources).Higher concentrations of MAs and PM1, OC and EC in winter seasons, could be caused not only by larger emissions from biomass or coal combustion, but also by less dispersion due to different atmospheric conditions.
Mostrar más [+] Menos [-]Three decadal inputs of total organic carbon from four major coastal river basins to the summer hypoxic zone of the Northern Gulf of Mexico Texto completo
2015
He, Songjie | Xu, YJun
This study investigated long-term (1980–2009) yields and variability of total organic carbon (TOC) from four major coastal rivers in Louisiana entering the Northern Gulf of Mexico where a large-area summer hypoxic zone has been occurring since the middle 1980s. Two of these rivers drain agriculture-intensive (>40%) watersheds, while the other two rivers drain forest-pasture dominated (>50%) watersheds. The study found that these rivers discharged a total of 13.0×104t TOC annually, fluctuating from 5.9×104 to 22.8×104t. Seasonally, the rivers showed high TOC yield during the winter and early spring months, corresponding to the seasonal trend of river discharge. While river hydrology controlled TOC yields, land use has played an important role in fluxes, seasonal variations, and characteristics of TOC. The findings fill in a critical information gap of quantity and quality of organic carbon transport from coastal watersheds to one of the world’s largest summer hypoxic zones.
Mostrar más [+] Menos [-]Water–oil separation performance of technical textiles used for marine pollution disasters Texto completo
2015
Seddighi, Mahdi | Hejazi, Sayyed Mahdi
Oil is principally one of the most important energy sources in the world. However, as long as oil is explored and transported for being used, there will be the risk of the spillage into the marine environment. The use of technical textiles, i.e. fibrous beds, is a conventional separation technique for oil/water emulsion since it is efficient and easy to design. In this paper, the recovery of oil by technical textiles was mathematically modeled based on the structural parameters of textile and the capillary mechanism. Eleven types of commercial technical textiles with different properties were prepared for the experimental program. The experimental design included fiber type (polypropylene and polyester), fabric type (woven and/or nonwoven), fabric thickness and fabric areal density. Consequently, the absorption capacities of different technical textile samples were derived by the use of theoretical and experimental methods. The results show that there is a well fitness between theoretical outputs and experimental data.
Mostrar más [+] Menos [-]Flow cytometric applicability to evaluate UV inactivation of phytoplankton in marine water samples Texto completo
2015
Olsen, Ranveig Ottoey | Hess-Erga, Ole-Kristian | Larsen, Aud | Thuestad, Gunnar | Tobiesen, August | Hoell, Ingunn Alne
Disinfection of microbes is of importance to prevent the spread of pathogens and non-indigenous species in the environment. Here we test the applicability of using flow cytometry (FCM) to evaluate inactivation of the phytoplankter Tetraselmis suecica after UV irradiation and labeling with the esterase substrate 5-carboxyfluorescein diacetate acetoxymethyl ester (CFDA-AM). Non-irradiated and UV irradiated samples were analyzed with the plate count technique and FCM for 24days. The numbers of colony forming units were used as a standard to develop a FCM protocol. Our protocol readily distinguishes live and dead cells, but challenges were encountered when determining whether UV damaged cells are dying or repairable. As damaged cells can represent a risk to aquatic organisms and/or humans, this was taken into account when developing the FCM protocol. In spite of the above mentioned challenges we argue that FCM represents an accurate and rapid method to analyze T. suecica samples.
Mostrar más [+] Menos [-]Litter and seabirds found across a longitudinal gradient in the South Pacific Ocean Texto completo
2015
Miranda-Urbina, Diego | Thiel, Martin | Luna-Jorquera, Guillermo
Abundances and composition of marine litter and seabirds were estimated in the central South Pacific (SP) Ocean between the Chilean continental coast and the Easter Island Ecoregion. Litter was dominated by plastics throughout the study area, but the proportion of plastics was higher at sea and on the oceanic islands than in coastal waters and on continental beaches. Litter densities were higher close to the center of the SP subtropical gyre compared to the continental coast. The seabird assemblage was diverse (28 species), and several endemic species were recorded. Seabird abundances were higher in the coastal waters and around Juan Fernández Islands off the continental coast than in the Oceanic and Polynesian sectors. Endangered species breeding on Salas & Gómez Island were observed in the Polynesian sector, which suggests a high potential for negative interactions between seabirds and floating litter, both occurring in high densities in this sector.
Mostrar más [+] Menos [-]New non-PBDE brominated flame retardants in sediment and plant samples from Jiaozhou Bay wetland Texto completo
2015
Wang, Ling | Zhao, Quansheng | Zhao, Yanyan | Zheng, Minggang | Lou, Yinghua | Yang, Baijuan
Seven non-polybrominated diphenyl ethers (non-PBDE) (TBB, TBX, PBT, PBEB, HBB, DBHCTD and BB153) were analyzed in sediment and plant samples which were collected from Xiaojianxi landfill to Dagu river estuary in Jiaozhou Bay wetland. The species of non-PBDE were different in sediment and plant samples with the concentration of 0.41–9.66ngg−1 and 0.15–1.2ngg−1, respectively. DBHCTD was the main non-PBDE compared with other target compounds and its concentration was 1.21–9.66ngg−1dw. Generally, the concentration of non-PBDE in sediment showed a decreasing tendency while discrete decline in plant has been revealed. Furthermore, DBHCTD, HBB, as well as other BFRs, might have a common BFRs degradation or similar accumulation potential in sediment, as their Pearson relationship p<0.05. Generally, the content of non-PBDE in Jiaozhou Bay wetland was higher than other published research. Therefore, more attention should be paid to non-PBDE on account of their persisting impact on human health and environment.
Mostrar más [+] Menos [-]Short-term dynamics of cyanobacterial toxins (microcystins) following a discharge from a coastal reservoir in Isahaya Bay, Japan Texto completo
2015
Umehara, Akira | Komorita, Tomohiro | Tai, Akira | Takahashi, Tohru | Orita, Ryo | Tsutsumi, Hiroaki
Freshwater cyanobacteria produce highly toxic substances such as microcystins (MCs), and water containing MCs is often discharged to downstream and coastal areas. We conducted field monitoring in Isahaya Bay to clarify the short-term dynamics of MCs discharged from a reservoir following a cyanobacteria bloom in the warm season. MCs were detected in the seawater of the bay (max. 0.10μgL−1), and were deposited on the sea floor, with the MC content of the surface sediment increasing by approximately five times (0.11±0.077–0.53±0.15μgkgww−1, mean±SD) at the four stations near the reservoir drainage gate before and after the discharge. The MCs was then transported from the mouth of the bay by tidal currents during the period of the study. Therefore, the MCs were moved away from the closed water area where the cyanobacteria blooms, and spread throughout the coastal area.
Mostrar más [+] Menos [-]Sterols as biomarkers in the surface microlayer of the estuarine areas Texto completo
2015
Alsalahi, Murad Ali | Latif, Mohd Talib | Ali, Masni Mohd | Dominick, Doreena | Khan, Md Firoz | Mustaffa, Nur Ili Hamizah | Nadzir, Mohd Shahrul Mohd | Nasher, Essam | Zakaria, Mohamad Pauzi
This study aims to determine the concentration of sterols used as biomarkers in the surface microlayer (SML) in estuarine areas of the Selangor River, Malaysia. Samples were collected during different seasons through the use of a rotation drum. The analysis of sterols was performed using gas chromatography equipped with a flame ionisation detector (GC–FID). The results showed that the concentrations of total sterols in the SML ranged from 107.06 to 505.55ngL−1. The total sterol concentration was found to be higher in the wet season. Cholesterol was found to be the most abundant sterols component in the SML. The diagnostic ratios of sterols show the influence of natural sources and waste on the contribution of sterols in the SML. Further analysis, using principal component analysis (PCA), showed distinct inputs of sterols derived from human activity (40.58%), terrigenous and plant inputs (22.59%) as well as phytoplankton and marine inputs (17.35%).
Mostrar más [+] Menos [-]The risk assessment of heavy metals in Futian mangrove forest sediment in Shenzhen Bay (South China) based on SEM–AVS analysis Texto completo
2015
Chai, Minwei | Shen, Xiaoxue | Li, Ruili | Qiu, Guoyu
The risks of heavy metal in Futian mangrove forest sediment were assessed using the acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) methods. The results indicated that AVS distributions were more variable than the SEM distributions at all 16 sampling sites. The positive correlation between AVS and SEM indicated that their similar formative and existing conditions and that AVS acted as an important carrier for SEM. The major SEM component was Zn (69.7.3–94.2%), whereas the Cd contribution (the most toxic metal present) to SEM was no more than 1%. The possible adverse effects caused by heavy metals at ten sampling sites may be due to higher levels of SEMs, rather than AVSs. The total organic carbon (TOC) was an important metal-binding phase in the sediments. Taking into account the TOC concentration, there were no adverse effects due to heavy metals in any of the Futian mangrove forest sediments.
Mostrar más [+] Menos [-]Submarine and deep-sea mine tailing placements: A review of current practices, environmental issues, natural analogs and knowledge gaps in Norway and internationally Texto completo
2015
Ramirez-Llodra, Eva | Trannum, Hilde C. | Evenset, Anita | Levin, Lisa A. | Andersson, Malin | Finne, Tor Erik | Hilario, Ana | Flem, Belinda | Christensen, Guttorm | Schaanning, Morten | Vanreusel, Ann
Submarine and deep-sea mine tailing placements: A review of current practices, environmental issues, natural analogs and knowledge gaps in Norway and internationally Texto completo
2015
Ramirez-Llodra, Eva | Trannum, Hilde C. | Evenset, Anita | Levin, Lisa A. | Andersson, Malin | Finne, Tor Erik | Hilario, Ana | Flem, Belinda | Christensen, Guttorm | Schaanning, Morten | Vanreusel, Ann
The mining sector is growing in parallel with societal demands for minerals. One of the most important environmental issues and economic burdens of industrial mining on land is the safe storage of the vast amounts of waste produced. Traditionally, tailings have been stored in land dams, but the lack of land availability, potential risk of dam failure and topography in coastal areas in certain countries results in increasing disposal of tailings into marine systems. This review describes the different submarine tailing disposal methods used in the world in general and in Norway in particular, their impact on the environment (e.g. hyper-sedimentation, toxicity, processes related to changes in grain shape and size, turbidity), current legislation and need for future research. Understanding these impacts on the habitat and biota is essential to assess potential ecosystem changes and to develop best available techniques and robust management plans.
Mostrar más [+] Menos [-]Submarine and deep-sea mine tailing placements: a review of current practices, environmental issues, natural analogs and knowledge gaps in Norway and internationally Texto completo
1000 | 2015
Ramirez-Llodra, Eva | Trannum, Hilde C. | Evenset, Anita | Levin, Lisa A. | Andersson, Malin | Finne, Tor Erik | Hilario, Ana | Flem, Belinda | Christensen, Guttorm | Schaanning, Morten | Vanreusel, Ann
The mining sector is growing in parallel with societal demands for minerals. One of the most important environmental issues and economic burdens of industrial mining on land is the safe storage of the vast amounts of waste produced. Traditionally, tailings have been stored in land dams, but the lack of land availability, potential risk of dam failure and topography in coastal areas in certain countries results in increasing disposal of tailings into marine systems. This review describes the different submarine tailing disposal methods used in the world in general and in Norway in particular, their impact on the environment (e.g. hyper-sedimentation, toxicity, processes related to changes in grain shape and size, turbidity), current legislation and need for future research. Understanding these impacts on the habitat and biota is essential to assess potential ecosystem changes and to develop best available techniques and robust management plans.
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